Function strbuf_append_ext_header

archive-tar.c:157–177

* pax extended header records have the format "%u %s=%s\n". %u contains * the size of the whole string (including the %u), the first %s is the * keyword, the second one is the value. This function constructs such a * string and appends it to a struct strbuf. */

 * string and appends it to a struct strbuf.
 */
static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
				     const char *value, size_t valuelen)
{
	size_t orig_len = sb->len;
	size_t len, tmp;

	/* "%u %s=%s\n" */
	len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
	for (tmp = 1; len / 10 >= tmp; tmp *= 10)
		len++;

	strbuf_grow(sb, len);
	strbuf_addf(sb, "%"PRIuMAX" %s=", (uintmax_t)len, keyword);
	strbuf_add(sb, value, valuelen);
	strbuf_addch(sb, '\n');

	if (len != sb->len - orig_len)
		BUG("pax extended header length miscalculated as %"PRIuMAX
		    ", should be %"PRIuMAX,
		    (uintmax_t)len, (uintmax_t)(sb->len - orig_len));
}

/*
 * Like strbuf_append_ext_header, but for numeric values.